The currently circulating IC cards include a lot of IC cards used without authentication of an owner, and a person obtaining such an IC card can browse or use the contents of the IC card.
Of course, IC cards used with authentication of an owner also have been proposed heretofore (cf. Patent Document 1 below) though they are still a minority.    Patent Document 1 is Japanese Patent Application Laid-Open Gazette No. 2000-163533.